1. Field of the Invention
This invention relates to a flexure used in a disk drive suspension for an information processing apparatus.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The HDD comprises a magnetic disk rotatable about a spindle, a carriage turnable about a pivot, etc. A disk drive suspension is disposed on an arm of the carriage.
The disk drive suspension comprises a load beam and flexure superposed thereon. A magnetic head comprising a slider is mounted on a gimbal portion formed near the distal end of the flexure. The magnetic head is provided with elements (transducers) for accessing data, that is, for reading or writing. The suspension, flexure, etc., constitute a head gimbal assembly.
The flexure is practically used in various forms depending on the required specifications. By way of example, it is a flexure with conductors, which comprises a thin metal base of stainless steel, insulating layer of an electrically insulating material, such as polyimide, and a plurality of pairs of copper conductors. The insulating layer is formed on the metal base, and the conductors on the insulating layer. Respective one ends of the conductors are connected to elements (e.g., magnetoresistive elements) on the magnetic head. The other ends of the conductors are electrically connected to an electrical circuit, such as an amplifier. These conductors constitute a conductive circuit portion of the suspension. The impedance of the conductors needs to be reduced in order to reduce energy consumption of the amplifier. Further, a high-frequency band is needed in order to increase the number of signals transmitted per unit time.
An example of the flexure with conductors is disclosed in Jpn. Pat, Appln. KOKAI Publication No. 9-282624 (Patent Document 1). A plurality of openings are formed in a metal base of the flexure so as to be arranged at regular intervals along the conductors. Since these openings serve to reduce the eddy current loss of a conductive circuit portion, attenuation in a high-frequency band is reduced. Another example of the flexure with conductors is disclosed in U.S. Pat. No. 6,714,385 (Patent Document 2). A plurality of openings are formed in a load beam of a suspension that comprises the flexure so as to be arranged at regular intervals along the conductors.
Suspensions tend to become further smaller as disk drives are miniaturized and improved in recording density. Conductors should be made wider in order to reduce the impedance of a conductive circuit portion of a flexure. The smaller the suspension, therefore, the higher the ratio of the mass of the conductive circuit portion to that of the suspension is. Therefore, the dynamic characteristics of the suspension are easily affected by the conductive circuit portion. Thus, the conductive circuit portion is required to be made lighter.
If the conductors are made narrower, however, the impedance increases, thereby causing an increase in energy consumption. If the width of each conductor is simply reduced, moreover, the attenuation in the high-frequency band may become too high for high-speed data transmission, depending on the configuration of the conductive circuit portion. Although the openings are formed in the metal base in the conductive circuit portion of Patent Document 1 described above, the weight reduction ratio is low if the conductor weight is the same as in the conventional case. Even if the openings are formed in the load beam, as in Patent Document 2, the conductive circuit portion of the flexure cannot be made lighter.